Preharvest sprays of fungicides to control gray mold by Botrytis cinerea in postharvest pear fruit in Argentina

SOSA, M.C.; LUTZ, M.C.; MANTEGNA, M.; ELDESTEIN, R.

Santa Cruz

Simposio; XVII international Btrytis symposium; 2016

Lab. de Fitopatología Frutal y Molecular, FCA Univ. de Chile

Botrytis cinerea is one of the main post-harvest pathogens, mainly affecting Beurre Bosc and Beurre D´Anjou pear fruit cultivars in the Patagonian orchards, Argentina. Decays by B. cinerea become from field latent fruits infections of calyxes and stems, orby wounds at harvest or post-harvest. Decays develop during the ripening of the fruit, causing significant economic losses. Due to the presence of latent infections, we propose to assess the use of new non register fungicides on pear fruit on the B. cinerea decay control. Sprays with fungicides were conducted in orchard of Beurre Bosc cultivar during the 2012/13 and 2013/14 growing season. In 2012/13, we studied the effect of pyraclostrobin (pyr) 12.8% w/w + boscalid (bos) 25.2% w/w, 50g?HL-1 and myclobutanil (mycl) 40% w/w 15g?HL-1 (registered for powdery mildew and scab), 30 days before harvest (DBH). In 2013/14, we evaluated pyr+bos and essential oils from Melaleuca alternifolia 0.06L?HL-1, 7 DBH. In both seasons, water was a control treatment. Fruit was harvested and storage at -1/0°C, and 98%RH. The incidence percentage (%I) of gray mold was evaluated on artificially wounded and unwounded fruits, in each preharvest treatment. In 2012/13, we observed that fungicides applied at preharvest significantly reduced the incidence of decays by B. cinerea at postharvest, after 120d of cold storage. The fruit treated with water (without fungicide) had 6 %I, while the fruit treated with pyr+bos and mycl had 0.3 %I (95% DR) and 1.55 %I (74% DR), respectively. In the wounded fruit at harvest, we observed 10.5 %I, whereas only 1 %I (92.7% DR) with pyr+bos and 1.5 %I (83 DR) with mycl. We also evaluated he effect of preharvest treatment plus fludioxonil (flu) 23 % w/v spray at postharvest. After 120 days, these treatments diminished on about 100% the decay incidence respect to the effect of flu alone. During 2013/14, after 100 days of cold storage, unwounded fruit had low incidence (1%I) of B. cinerea and it was not observed differences between treatments. However, pyr+bos and oils of M. alternifolia reduced the decays by Alternaria in about 30 and 48 %, respectively. In relation to wounded fruits, was demonstrated the effect on decays, diminished from 10%I on the water alone treatment to 5 and 2,3% with the fungicide treated fruits. These promissory results become as the first contribution about the use of new fungicide in preharvest in order to reduce the pear fruit postharvest decay in Argentina.